Yuri Kuchinsky wrote:

Gary Coffman wrote:

On Mon, 28 Jun 2004 09:04:49 +1200, Eric Stevens wrote:

On Sun, 27 Jun 2004 03:03:50 -0400, Gary Coffman
wrote:

On Wed, 23 Jun 2004 23:46:01 -0500, Tom McDonald wrote:

Eric Stevens wrote:

On Fri, 11 Jun 2004 22:57:04 GMT, (Gary Coffman)
wrote:

But that said, casting pure copper is a bitch.


This from the guy who has just written that the task can be undertaken
by low-skilled workers?

Eric, I read that to mean that casting, in general (as with
iron, silver, bronze, gold, etc.) can be done by folks with
fewer skills than smiths. However, copper appears to present
particular problems with casting that are not so pronounced with
other metals, and which require higher skill levels than would
be required by those who cast other metals.

Exactly, and further, skill alone isn't sufficient to make sound
castings of pure copper. The proper equipment is also required.
Specifically, an inert atmosphere furnace. That technology
didn't exist until the late 19th century.

Just as well the ancient egyptians didn't know that they couldn't do
what they were doing. :-)

So, are you claiming to have evidence that the ancient Egyptians
successfully cast pure native copper?

The metallurgical references I have say that native copper was
extremely rare in Egypt. Almost all of the copper they had was
refined from ores (smelted), and the results were *not* pure
copper. Rather, they were alloys, whether intentional or not,
of copper, arsenic, zinc, iron, or tin. These alloys behave *very*
differently from pure native copper when casting is attempted.

Gary


Well, Gary, the folowing sure seems to imply that the
ancient Egyptian did some copper casting.

[quote]

Ancient Egyptian raw materials: metals - copper, bronze,
iron, gold, silver, lead
http://nefertiti.iwebland.com/trades/metals.htm


copper objects [rather than bronze]:

The objects were generally cast, which is quite difficult to
do with copper because of the formation of gas bubbles
during the pouring of the metal and its shrinking when it
cooled down. Then they were hammered cold to give them their
final form.

[unquote]

Yuri,

Your site tells us that copper ore was what was available, not
native copper; and that it had to be smelted before use. IOW,
it's not clear whether the Egyptians ever had copper of the
purity of the native copper in the upper Great Lakes area. In
addition, the smelting and melting of that copper would more
than likely have resulted in a copper alloy, not pure copper.

Of course, if you have better evidence that shows Egyptians
cast 99+% pure copper, you are welcome to present it here. I
for one would be very interested in that evidence.

Tom McDonald